Composition for forming anti-reflective coating

ABSTRACT

There is provided a composition for forming anti-reflective coating for use in a lithography process with irradiation light from F2 excimer laser (wavelength 157 nm) which has a high effect of inhibiting reflected light and causes no intermixing with resist layers, and an anti-reflective coating prepared from the composition, and a method of controlling attenuation coefficient of the anti-reflective coating. 
     Concretely, the composition is one containing a polymer compound containing halogen atom for forming anti-reflective coating for use in a lithographic process in manufacture of a semiconductor device. The polymer compound is one which halogen atom is introduced to a main chain thereof and/or a side chain bonded to the main chain. The attenuation coefficient can be controlled by changing the content of halogen atom in the solid content of the composition.

TECHNICAL FIELD

The present invention relates to a composition for forminganti-reflective coating, particularly to a composition for reducing areflection of irradiation light for exposing a photoresist applied on asubstrate from the substrate in a lithography process for manufacturinga semiconductor device, and more particularly to a composition forforming anti-reflective coating comprising a polymer compoundcomposition effectively absorbing reflection light from the substrate ina lithography process for manufacturing a semiconductor device by use ofirradiation light for exposure with a wavelength of 157 nm.

BACKGROUND ART

Conventionally, in the manufacture of semiconductor devices,micro-processing by lithography using a photoresist composition has beencarried out. The micro-processing is a processing method includingforming a thin film of a photoresist composition on a silicon wafer,irradiating actinic rays such as ultraviolet rays through a mask patterndepicting a pattern for a semiconductor device, developing it to obtaina resist pattern, and etching the silicon wafer using the resist patternas a protective film. However, in recent progress in high integration ofsemiconductor devices, there has been a tendency that shorter wavelengthactinic rays are being used, i.e., ArF excimer laser beam (wavelength193 nm) have been taking the place of i-line (wavelength 365 nm) or KrFexcimer laser beam (wavelength 248 nm). Along with this change,influences of random reflection and standing wave off a substrate havebecome serious problems. Accordingly, it has been widely studied toprovide an anti-reflective coating between the photoresist and thesubstrate (Bottom Anti-Reflective Coating, BARC). In addition, it comesto be considered to utilize F2 excimer laser (wavelength 157 nm) being alight source with a shorter wavelength for micro-processing bylithography.

As the anti-reflective coating, inorganic anti-reflective coatings madeof titanium, titanium dioxide, titanium nitride, chromium oxide, carbonor α-silicon and organic anti-reflective coatings made of alight-absorbing substance and a polymer compound are known. The formerrequires an installation such as a vacuum deposition apparatus, a CVD(chemical vapor deposition) apparatus or a sputtering apparatus. Incontrast, the latter is considered advantageous in that it requires nospecial installation so that many studies have been made. For example,mention may be made of the acrylic resin type anti-reflective coatinghaving a hydroxyl group being a crosslinking reaction group and a lightabsorbing group in the same molecule and the novolak resin typeanti-reflective coating having a hydroxyl group being a crosslinkingreaction group and a light absorbing group in the same molecule (see,for example U.S. Pat. Nos. 5,919,599 and 5,693,691).

The physical properties desired for organic anti-reflective coatingmaterials include high absorbance to light and radioactive rays, nointermixing with the photoresist layer (being insoluble in photoresistsolvents), no diffusion of low molecular substances from theanti-reflective coating material into the topcoat resist upon coating orheat-drying, and a higher dry etching rate than the photoresist (see,for example, Tom Lynch et al., “Properties and Performance of Near UVReflectivity Control Layers”, US, in Advances in Resist Technology andProcessing XI, Omkaram Nalamasu ed., Proceedings of SPIE, 1994, Vol.2195, p. 225-229; G. Taylor et al., “Methacrylate Resist andAntireflective Coatings for 193 nm Lithography”, US, in Microlithography1999: in Advances in Resist Technology and Processing XVI, Will Conleyed., Proceedings of SPIE, 1999, Vol. 3678, p. 174-185; and Jim D. Meadoret al., “Recent Progress in 193 nm Antireflective Coatings, US, inMicrolithography 1999: in Advances in Resist Technology and ProcessingXVI, Will Conley ed., Proceedings of SPIE, 1999, Vol. 3678, p. 800-809).

By the way, a hitherto technique of anti-reflective coatings has beenmainly considered on lithography process with irradiation light having awavelength of 365 nm, 248 nm or 193 nm. As a result of suchconsideration, light absorbing components and light absorbing groupseffectively absorbing light of each wavelength are developed, and theycome to be utilized as one component of an organic anti-reflectivecoating composition. For example, it is known that chalcone diesprepared by condensation of 4-hydroxyacetophenone with4-methoxybenzaldehyde are effective for irradiation light having awavelength of 365 nm (see, for example Japanese Patent Laid-open No. Hei11-511194), it is known that naphthalene group-containing polymershaving a specific structure have high absorbance for irradiation lighthaving a wavelength of 248 nm (see, for example Japanese PatentLaid-open No. Hei 10-186671), and it is known that resin bindercompositions containing phenyl unit are excellent for irradiation lighthaving a wavelength of 193 nm (see, for example Japanese PatentLaid-open No. 2000-187331).

In recent years, lithography process with F2 excimer laser (wavelength157 nm) being a light source having a shorter wavelength comes to beregarded as next-generation technology in place of that with ArF excimerlaser (wavelength 193 nm). It is considered that the former processpermits micro-processing of process dimension not more than 100 nm, andat present its development and research have been actively carried outfrom the aspects of apparatus and material, etc. However, most of theresearch on material relate to photoresist, and it is an actualcondition that the research on organic anti-reflective coatings islittle known. This is because components effectively absorbing lighthaving a wavelength of 157 nm, that is light absorbing components havinga strong absorption band at 157 nm are little known.

It is considered that as irradiation light provides process dimensionnot more than 100 nm. Therefore, it is also considered that aphotoresist is used in a form of thin film having a thickness of 100 to300 nm that is thinner compared with the prior one. Organicanti-reflective coatings used along with such a photoresist in a form ofthin film require the followings: they can be used in a form of a thinfilm; and they have a high selectivity of dry etching for photoresist.And, it is considered that organic anti-reflective coatings are requiredto have a large attenuation coefficient k so that they could be used ina shape of thin film having a thickness of 30 to 80 nm. In a simulationwith PROLITH ver. 5 (manufactured by Litho Tech Japan; expected andideal values are used as optical constants (refractive index,attenuation coefficient) of the photoresist), an anti-reflective coatinghaving a base substrate made of silicon with a thickness of 30 to 80 nmcan have second minimum thickness (about 70 nm), and in this case thecoating has an attenuation coefficient k of 0.3 to 0.6 and a reflectancefrom substrate of 2% or less, thus has a sufficient anti-reflectiveeffect. In addition, a similar simulation in which silicon oxide is usedas base substance and a thickness of silicon oxide varies between 100 nmand 200 nm results in that attenuation coefficient k of 0.4 to 0.6 isrequired in order to exert a sufficient anti-reflective effect with ananti-reflective coating having a thickness of 70 nm. For example, incase where attenuation coefficient k is 0.2, reflectance from substratevaries between 5% and 10%, and in case where attenuation coefficient kis 0.4, reflectance from substrate varies between 0% and 5%.Consequently, it is considered that in order to exert a sufficientanti-reflective effect, a high attenuation coefficient k, for example0.3 or more is required. However, any material for organicanti-reflective coatings satisfying such an attenuation coefficient khave been little known.

Under such circumstances, it is demanded to develop organicanti-reflective coatings efficiently absorbing reflection light frombase substrate and thereby having an excellent anti-reflective effect.

Further, photoresists for lithography process for which irradiationlight from F2 excimer laser are used are actively examined at present,and therefore it is considered that many kinds of photoresists will bedeveloped in future. And, it is considered that a method of changingattenuation coefficient so as to suit required characteristics of eachphotoresist, for example a method of changing attenuation coefficient kcomes to be important.

In the meanwhile, it is known that anti-reflective coating compositionscontaining fluorine-containing polymer is applied to lithographytechnique with F2 excimer laser as light source (see, for example,Japanese Patent Laid-open Nos. 2002-236370 and 2002-198283).

The present invention relates to a composition for forminganti-reflective coating, which has a strong absorption of light at ashort wavelength, particularly light at wavelength of 157 nm. Inaddition, the present invention provides a composition for forminganti-reflective coating, which can be used in a lithography process formanufacturing a semiconductor device carried out by using irradiationlight from F2 excimer laser (wavelength 157 nm). Further, the presentinvention provides an anti-reflective coating for lithography whicheffectively absorbs reflection light from a substrate when irradiationlight from F2 excimer laser (wavelength 157 nm) is used formicro-processing, and which causes no intermixing with photoresistlayer, and a composition for forming the anti-reflective coating. Inaddition, the present invention provides a method of forming ananti-reflective coating for lithography by using the composition forforming anti-reflective coating, and a method of forming a photoresistpattern. Further, the present invention provides a method of controllingattenuation coefficient k which is one of main characteristics ofanti-reflective coating.

DISCLOSURE OF THE INVENTION

The present invention relates to the following aspects:

-   -   as a first aspect, a composition for forming anti-reflective        coating characterized in that the composition comprises a solid        content and a solvent, and a proportion of halogen atom in the        solid content is 10 mass % to 60 mass %;    -   as a second aspect, the composition for forming anti-reflective        coating as described in the first aspect, wherein the solid        content contains a polymer compound having a repeating        structural unit containing a halogen atom;    -   as a third aspect, the composition for forming anti-reflective        coating as described in the first aspect, wherein the solid        content contains a polymer compound having a repeating        structural unit containing a halogen atom and a        crosslink-forming substituent;    -   as a fourth aspect, the composition for forming anti-reflective        coating as described in the first aspect, wherein the solid        content contains a polymer compound having a repeating        structural unit containing a halogen atom and a repeating        structural unit containing a crosslink-forming substituent;    -   as a fifth aspect, a composition for forming anti-reflective        coating characterized in that the composition contains a polymer        compound having a repeating structural unit containing a halogen        atom, and an attenuation coefficient k of a coating formed from        the composition to light at a wavelength of 157 nm is 0.20 to        0.50;    -   as a sixth aspect, a composition for forming anti-reflective        coating characterized in that the composition contains a polymer        compound having a repeating structural unit containing a halogen        atom and a crosslink-forming substituent, and an attenuation        coefficient k of a coating formed from the composition to light        at a wavelength of 157 nm is 0.20 to 0.50;    -   as a seventh aspect, a composition for forming anti-reflective        coating characterized in that the composition contains a polymer        compound having a repeating structural unit containing a halogen        atom and a repeating structural unit containing a        crosslink-forming substituent, and an attenuation coefficient k        of a coating formed from the composition to light at a        wavelength of 157 nm is 0.20 to 0.50;    -   as an eighth aspect, the composition for forming anti-reflective        coating as described in any one of the second to seventh        aspects, wherein the polymer compound contains at least one        halogen atom selected from chlorine atom, bromine atom and        iodine atom;    -   as a ninth aspect, the composition for forming anti-reflective        coating as described in any one of the second to eighth aspects,        wherein the polymer compound contains at least 10 mass % of a        halogen atom;    -   as a tenth aspect, the composition for forming anti-reflective        coating as described in any one of the second to ninth aspects,        wherein the polymer compound has a weight average molecular        weight of 700 to 1,000,000;    -   as an eleventh aspect, the composition for forming        anti-reflective coating as described in the third or sixth        aspect, wherein the repeating structural unit containing a        halogen atom and a crosslink-forming substituent is represented        by formula (1)

wherein L is a bonding group constituting a main chain of the polymercompound, M is a linking group containing at least one linking groupselected from —C(═O)—, —CH₂— or —O—, or a direct bond, X is bromine atomor iodine atom, t is a number of 1 or 2, u is a number of 2, 3 or 4, vis a number of the repeating structural units contained in the polymercompound and is a number of 1 to 3,000;

-   -   as a twelfth aspect, the composition for forming anti-reflective        coating as described in any one of the first to eleventh        aspects, wherein the solid content further contains a        crosslinking agent having at least two crosslink-forming        substituents;    -   as a thirteenth aspect, a method of forming an anti-reflective        coating for use in a manufacture of a semiconductor device,        comprising the steps of: coating the composition for forming        anti-reflective coating as described in any one of the first to        twelfth aspects on a substrate, and baking it;    -   as a fourteenth aspect, a method of forming an anti-reflective        coating for use in a manufacture of a semiconductor device by        use of a light of wavelength 157 nm, comprising the steps of:        coating the composition for forming anti-reflective coating as        described in any one of the first to twelfth aspects on a        substrate, and baking it;    -   as a fifteenth aspect, an anti-reflective coating produced by        coating the composition for forming anti-reflective coating as        described in any one of the first to twelfth aspects on a        semiconductor substrate, and baking it, wherein the        anti-reflective coating has an attenuation coefficient k to a        light at a wavelength of 157 nm ranging from 0.20 to 0.50;    -   as a sixteenth aspect, a method of forming an anti-reflective        coating for use in a manufacture of a semiconductor device, in        which an attenuation coefficient k is altered by changing a        content of a halogen atom in the anti-reflective coating;    -   as a seventeenth aspect, a method of forming an anti-reflective        coating for use in a manufacture of a semiconductor device, in        which an attenuation coefficient k to a light at a wavelength of        157 nm is altered by changing a content of a halogen atom in the        anti-reflective coating;    -   as an eighteenth aspect, a method of forming a photoresist for        use in a manufacture of a semiconductor device comprising the        steps of:        -   coating the composition for forming anti-reflective coating            according to any one of the first to twelfth aspects on a            semiconductor substrate and baking it to form an            anti-reflective coating,        -   forming a photoresist layer on the anti-reflective coating,        -   exposing the semiconductor substrate covered with the            anti-reflective coating and the photoresist layer with F2            excimer laser (wavelength 157 nm), and        -   developing the exposed photoresist layer.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a composition for forminganti-reflective coating consisting of a solid content containing ahalogen atom-containing component and a solvent. In addition, thepresent invention relates to a composition for forming anti-reflectivecoating characterized by containing as halogen atom-containing componenta polymer compound having a repeating structural unit containing ahalogen atom. Further, the present invention relates to a compositionfor forming anti-reflective coating, which can be used in lithographyprocess for manufacturing a semiconductor device by use of irradiationlight of a short wavelength, particularly irradiation light of F2excimer laser (wavelength 157 nm).

The composition for forming anti-reflective coating according to thepresent invention basically comprises a polymer compound having arepeating structural unit containing a halogen atom, and a solvent; apolymer compound having a repeating structural unit containing a halogenatom and a crosslink-forming substituent, and a solvent; or a polymercompound having a repeating structural unit containing a halogen atomand a repeating structural unit containing a crosslink-formingsubstituent, and a solvent, and as arbitrary component a catalyst forcrosslinking, a surfactant and the like. The composition for forminganti-reflective coating according to the present invention contains 0.1to 50 mass %, preferably 0.5 to 30 mass % of solid content. In thisspecification, the solid content means components other than the solventin the composition for forming anti-reflective coating.

The molecular weight of the polymer compound containing a halogen atomranges from 700 to 1,000,000, preferably from 700 to 500,000, and morepreferably 900 to 300,000 in terms of weight average molecular weightalthough it may vary depending on the coating solvents used, theviscosity of the solution, the shape of the coating, etc.

The polymer compound in the present invention is a compound containingat least one kind of halogen atom selected from chlorine atom, bromineatom and iodine atom in the main chain and/or side chain constitutingit. The halogen atom to be contained may be one kind, two kinds or threekinds, and preferably is bromine atom or iodine atom. The polymercompound contains preferably at least 10 mass %, more preferably 10 to80 mass %, further preferably 20 to 70 mass % of halogen atom. Thecontent of the polymer compound in the composition for forminganti-reflective coating according to the present invention is 20 mass %or more in the solid content, for example 20 mass % to 100 mass %, or 30mass % to 100 mass %, or 50 mass % to 90 mass %, or 60 mass % to 80 mass%.

The polymer compound may contain a crosslink-forming substituent. Thecrosslink-forming substituent includes amino group, hydroxy group,carboxy group, thiol group, and the like, and these substituents areintroduced in the main chain and/or side chain of the polymer compound.The crosslink-forming substituents to be introduced are the same ordifferent. In case where the crosslinking agent component is containedin the composition for forming anti-reflective coating according to thepresent invention, the crosslink-forming substituents can take place acrosslink-forming reaction with the crosslinking agent component onbaking under heating. The crosslink formation exerts an effect ofpreventing any intermixing between an anti-reflective coating formed bybaking and a photoresist applied thereon.

The polymer compound containing halogen atom can be synthesized by apolymerization reaction of unit monomer containing halogen atom, or apolymerization reaction of unit monomer containing halogen atom withunit monomer containing no halogen atom, or by a reaction of a polymerobtained by a polymerization reaction of unit monomer containing nohalogen atom with a compound containing halogen atom. Further, thepolymer compound can be synthesized by reacting a polymer obtained by apolymerization reaction of unit monomer containing halogen atom or apolymerization reaction of unit monomer containing halogen atom withunit monomer containing no halogen atom, with a compound containinghalogen atom or a compound containing no halogen atom. The content (mass%) of halogen atom in the polymer compound can be controlled by reactingthe polymer obtained by the polymerization reaction with a compoundcontaining halogen atom or a compound containing no halogen atom.

The unit monomers used for the polymerization reaction may be the sameeach other, and two kinds or more of the unit monomers may be used. Thepolymer compound formed from unit monomers can be synthesized by variousmethods such as radical polymerization, anionic polymerization, cationicpolymerization or condensation polymeization. As the type ofpolymerization, various methods such as solution polymerization,suspension polymerization, emulsion polymerization or bulkpolymerization are possible.

The unit monomers include for example compounds having additionpolymerizable unsaturated bond, such as acrylic acids, acrylic esters,acrylic amides, methacrylic acids, methacrylic esters, methacrylicamides, vinyl ethers, vinyl alcohols, vinyl ketones, styrenes, vinylphenols, maleic anhydrides or maleimides, each of which contains halogenatom. In addition, they include condensation polymerizable compoundssuch as dicarboxylic acid compounds, dihydroxy compounds, diaminocompounds, diepoxy compounds, diisocyanate compounds, acid dianhydridecompounds, dithiol compounds or phenol compounds, each of which containshalogen atom.

The unit monomer containing no halogen atom include for examplecompounds having addition polymerizable unsaturated bond, such asacrylic acids, acrylic esters, acrylic amides, methacrylic acids,methacrylic esters, methacrylic amides, vinyl ethers, vinyl alcohols,vinyl ketones, styrenes, vinyl phenols, maleic anhydrides or maleimides,each of which contains no halogen atom. In addition, they includecondensation polymerizable compounds such as dicarboxylic acidcompounds, dihydroxy compounds, diamino compounds, diepoxy compounds,diisocyanate compounds, acid dianhydride compounds, dithiol compounds orphenol compounds, each of which contains no halogen atom.

As compound containing halogen atom with which a polymer obtained bypolymerization reaction of the unit monomer containing no halogen atomis reacted, any compounds which can be reacted with the polymer can beused. For example, in case where there is a hydroxy group in thepolymer, the compounds include acid chlorides, epoxy compounds,isocyanate compounds and the like, each of which contains halogen atom.In case where there is an epoxy group in the polymer, the compoundsinclude hydroxy compounds, carboxylic acid compounds, thiol compoundsand the like, each of which contains halogen atom. In case where thereis an acid anhydride moiety in the polymer, the compounds includehydroxy compounds, amino compounds, thiol compounds and the like, eachof which contains halogen atom. In addition, in case where a carboxylgroup in the polymer, the compounds include hydroxy compounds, aminocompounds, thiol compounds, epoxy compounds and the like, each of whichcontains halogen atom.

The above-mentioned polymer compounds include for example polyacrylate,polyacrylamide, polymethacrylate, polymethacrylamide, polyvinyl ester,polyvinyl ether, polyvinyl alcohol, polyvinyl ketone, polystyrene,polyvinyl phenol and the like, each of which contains halogen atom andwhich may be a homopolymer or copolymer. In addition, they includecopolymers of acrylates with styrenes, copolymers of acrylates withmethacrylates, copolymers of acrylates with vinyl ethers, copolymers ofacrylates with vinyl esters, copolymers of methacrylates with styrenes,copolymers of methacrylates with methacrylamides, copolymers ofmethacrylates with vinyl ethers, copolymers of methacrylates with vinylalcohols, copolymers of methacrylates with vinyl esters, copolymers ofmethacrylates with vinyl phenols, copolymers of vinyl ethers withstyrenes, copolymers of vinyl alcohols with styrenes, terpolymers ofmethacrylates, styrenes and vinyl alcohols, terpolymers of acrylates,styrenes and vinyl esters, terpolymers of acrylates, methacrylates andvinyl esters, terpolymers of methacrylates, vinyl esters and vinylalcohols, each of which contains halogen atom. They includepolyurethane, polyester, polyether, polyurea, polyimide, novolak resinand the like, each of which contains halogen atom. Further, they includepolymer compounds containing a halogen atom which contain a unit monomersuch as maleic anhydride, maleimide or acrylonitrile.

The repeating structural unit containing a halogen atom and acrosslink-forming substituent which is contained in the polymer compoundin the composition for forming anti-reflective coating according to thepresent invention includes structural unit of formula (1)

wherein L is a bonding group constituting a main chain of the polymercompound, M is a linking group containing at least one linking groupselected from —C(═O)—, —CH2— or —O—, or a direct bond, X is bromine atomor iodine atom, t is a number of 1 or 2, u is a number of 2, 3 or 4, vis a number of the repeating structural units contained in the polymercompound and is a number of 1 to 3,000.

L is not specifically limited so long as it is a bonding groupconstituting a main chain of the polymer compound, and includes forexample the bonding groups of formulae (a-1) to (a-6).

M is a direct bond, or a linking group such as —C(═O)—, —C(═O)O—, —CH₂—,—O—, —C(═O)O—CH₂—, —C(═O)—NH—, —C(═O)—NH—CH₂—, —OC(═O)— or —OC(═O)—CH₂—,etc., and further linking groups of formulae (b-1) to (b-8).

In addition, the benzene ring portion of formula (1) include for examplethe structures of formulae (c-1) to (c-5).

The followings are concrete examples of the repeating structural unitcontaining a halogen atom which is contained in the polymer compound(formulae [1-1] to [1-34]), the repeating structural unit containing ahalogen atom and a crosslink-forming substituent (formulae [2-1] to[2-33]), and the repeating structural unit containing acrosslink-forming substituent ([formulae [3-1] to [3-10]), to which thepresent invention is not limited.

The followings are concrete examples of the polymer compound (formulae[4-1] to [4-47]) in the present invention, to which the presentinvention is not limited (in the formulae, p, q, r and s are molar ratioof the corresponding constituent unit monomer in the polymer compound,and v is the number of the repeated constituent unit monomers).

The composition for forming anti-reflective coating according to thepresent invention can alter the content (mass %) of halogen atomcontained in the polymer compound in the composition. That is, theselection of main chain structure of polymer compound, the selection ofkind of unit monomer used for the synthesis of polymer compound, theselection of kind of compound with which the polymer obtained by thepolymerization reaction is reacted, the selection of number and kind ofhalogen atom contained in the polymer compound make possible to alterthe content (mass %) of halogen atom contained in the polymer compound.The use of polymer compound with different content (mass %) of halogenatom makes possible to alter the content (mass %) of halogen atom in thesolid content of the anti-reflective coating, that is, the content (mass%) of halogen atom in the formed anti-reflective coating. And it ispossible to control attenuation coefficient k of anti-reflective coatingby altering the content (mass %) of halogen atom in the formedanti-reflective coating. In addition, it is also possible to alter thecontent (mass %) of halogen atom in the formed anti-reflective coatingby changing the proportion in the solid content of polymer compoundcontaining halogen atom in a constant content. Therefore, it is alsopossible to control attenuation coefficient k of anti-reflective coatingaccording to this process. In the meanwhile, in this specification, thesolid content means components other than the solvent in composition forforming anti-reflective coating, and the content (mass %) of halogenatom in the formed anti-reflective coating means the content (mass %) ofhalogen atom in the solid content of the composition for forminganti-reflective coating.

It is required that the solid content in the composition for forminganti-reflective coating according to the present invention contains atleast 10 mass % of halogen atom so that the anti-reflective coatingformed from the composition for forming anti-reflective coating couldsufficiently absorb a light from F2 excimer laser (wavelength 157 nm).The proportion of halogen atom in the solid content of the compositionfor forming anti-reflective coating according to the present inventionis 10 mass % to 60 mass %, or 15 mass % to 55 mass %, or 20 mass % to 50mass %. The halogen atom in the solid content of the composition forforming anti-reflective coating according to the present invention ischlorine atom, bromine atom or iodine atom, and preferably bromine atomor iodine atom.

The halogen atom in the solid content of the composition for forminganti-reflective coating according to the present invention is containedin the polymer compound as mentioned above. Alternatively, a compoundcontaining halogen atom may be added to the composition for forminganti-reflective coating.

The compound containing halogen atom includes for example a compoundhaving crosslink-forming substituent, such as 4-bromobenzoic acid,3-iodobenzoic acid, 2,4,6-tribromophenol, 2,4,6-tribromoresorcinol,2,4,6-triiodophenol, 4-iodo-2-methylphenol, 5-iodo methyl salicylate,3,4,5-triiodobenzoic acid, 2,4,6-triiodo-3-aminobenzoic acid,5-amino-2,4,6-triiodoisophthalic acid,5-hydroxy-2,4,6-triiodoisophthalic acid, 2,4,6-tribromobenzoic acid,2-amino4,5-dibromo-3,6-dimethylbenzoic acid,3,5-dibromo-4-hydroxybenzoic acid, 3,5-dibromo-2,4-dihydroxybenzoicacid, 3,5-diiodo-2-hydroxybenzoic acid, 2,4,6-triiodo-3-hydroxybenzoicacid or 2,4,6-tribromo-3-hydroxybenzoic acid.

The anti-reflective coating forming composition according to the presentinvention is preferably crosslinked after application by heating inorder to prevent intermixing with a photoresist applied thereon. Inaddition, the anti-reflective coating forming composition according tothe present invention may further contain a crosslinking agentcomponent. The crosslinking agent includes melamines and substitutedureas having crosslink-forming substituents such as methylol ormethoxymethyl groups, or polymer compounds having epoxy groups, and thelike. Preferable crosslinking agents are ones having at least twocrosslink-forming substituents, for example, compounds such asmethoxymethylated glycoluril, methoxymethylated melamine, morepreferably tetramethoxymethyl glycoluril or hexamethoxymethyl melamine.Further, the crosslinking agents include compounds such astetramethoxymethyl urea or tetrabutoxymethyl urea. The addition amountof the crosslinking agent may vary depending on the coating solventsused, the underlying substrate used, the viscosity of the solutionrequired, the shape of the coating required, etc., and usually 0.001 to20 mass %, preferably 0.01 to 15 mass %, more preferably 0.05 to 10 mass% in the total composition. These crosslinking agents occasionally occura crosslinking reaction due to self-condensation, but in case where acrosslink-forming substituent is present in the polymer compound in thepresent invention, the crosslinking agents can react with thecrosslink-forming substituent.

As catalyst for promoting the above-mentioned crosslinking reaction inthe present invention, acid compounds, such as p-toluenesulfonic acid,trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate, salicylicacid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoicacid, etc. or/and thermal acid generators, such as2,4,4,6-tetrabromocyclohexadienone, benzointosylate,2-nitrobenzyltosylate, etc. may be added. The blending amount thereof is0.02 to 10 mass %, preferably 0.04 to 5 mass % based on 100 mass % ofthe total solid content.

The anti-reflective coating composition according to the presentinvention may contain photoacid generators in order to adjust theacidity to that of a photoresist applied thereon in the lithographyprocess. Preferable photoacid generators include for example onium saltphotoacid generators, such as bis(4-t-butylpheny)iodoniumtrifluoromethanesulfonate or triphenylsulfoniumtrifluoromethanesulfonate, halogen-containing photoacid generators, suchas phenyl-bis(trichloromethyl)-s-triazine, sulfonate photoacidgenerators, such as benzoin tosylate or N-hydroxysuccinimidetrifluoromethanesulfonate. The photoacid generators are added in anamount of 0.2 to 3 mass %, preferably 0.4 to 2 mass % based on 100 mass% of the total solid content.

The anti-reflective coating forming composition according to the presentinvention may contain further light absorbing agents, rheologycontrolling agents, adhesion auxiliaries, surfactants, etc. in additionto the above described ones, if necessary.

As the further light absorbing agents, the followings can be suitablyused: for example commercially available light absorbing agentsdescribed in “Technique and Market of Industrial Pigments” (CMCPublishing Co., Ltd.) or “Dye Handbook” (edited by The Society ofSynthetic Organic Chemistry, Japan), such as C. I. Disperse Yellow 1, 3,4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90,93, 102, 114 and 124; C. I. Disperse Orange 1, 5, 13, 25, 29, 30, 31,44, 57, 72 and 73; C. I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54,58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; C. I. Disperse Violet43; C. I. Disperse Blue 96; C. I. Fluorescent Brightening Agent 112, 135and 163; C. I. Solvent Orange 2 and 45; C. I. Solvent Red 1, 3, 8, 23,24, 25, 27 and 49; C. I. Pigment Green 10; C. I. Pigment Brown 2, andthe others. The light absorbing agent is usually blended in an amount of10 mass % or less, preferably 5 mass % or less based on 100 mass % ofthe total composition.

The rheology controlling agents are added mainly aiming at increasingthe flowability of the anti-reflective coating forming composition andin particular in the baking step, increasing filling property of theanti-reflective coating forming composition into the inside of holes.Specific examples thereof include phthalic acid derivatives such asdimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexylphthalate or butyl isodecyl phthalate; adipic acid derivatives such asdi-n-butyl adipate, diisobutyl adipate, diisooctyl adipate or octyldecyladipate; maleic acid derivatives such as di-n-butyl maleate, diethylmaleate or dinonyl maleate; oleic acid derivatives such as methyloleate, butyl oleate or tetrahydrofurfuryl oleate; or stearic acidderivatives such as n-butyl stearate or glyceryl stearate. The rheologycontrolling agents are blended in proportions of usually less than 30mass % based on 100 mass % of the total composition.

The adhesion auxiliaries are added mainly for the purpose of increasingthe adhesion between the substrate or photoresist and theanti-reflective coating forming composition, in particular preventingthe detachment of the photoresist in development. Specific examplesthereof include chlorosilanes such as trimethylchlorosilane,dimethylvinylchlorosilane, methyidiphenylchlorosilane orchloromethyldimethyl-chlorosilane; alkoxysilanes such astrimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane,dimethylvinylethoxysilane, diphenyldimethoxysilane orphenyltriethoxysilane; silazanes such as hexamethyldisilazane,N,N′-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine ortrimethylsilylimidazole; silanes such as vinyltrichlorosilane,γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxy-silane orγ-glycidoxypropyltrimethoxysilane; heterocyclic compounds such asbenzotriazole, benzimidazole, indazole, imidazole,2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole,urazole, thiouracyl, mercaptoimidazole or mercaptopyrimidine; ureas suchas 1,1-dimethylurea or 1,3-dimethylurea, or thiourea compounds. Theadhesion auxiliaries are added in proportions of usually less than 5mass %, preferably less than 2 mass %, based on 100 mass % of the totalcomposition of the anti-reflective coating for lithography.

The anti-reflective coating forming composition according to the presentinvention may contain surfactants with view to preventing the occurrenceof pinholes or striations and further increasing coatability not tocause surface unevenness. As the surfactants, mention may be made of,for example, nonionic surfactants such as polyoxyethylene alkyl ethers,e.g., polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, etc.,polyoxyethylene alkyl allyl ethers, e.g., polyoxyethylene octyl phenolether, polyoxyethylene nonyl phenol ether;polyoxyethylene/polyoxypropylene block copolymers, sorbitan fatty acidesters, e.g., sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan monooleate, sorbitan trioleate, sorbitantristearate, etc., polyoxyethylene sorbitan fatty acid esters, e.g.,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, etc.; fluorinebased surfactants, e.g., EFTOP EF301, EF303, EF352 (Tochem Products Co.,Ltd.), MEGAFAC F171, F173 (Dainippon Ink and Chemicals, Inc.), FLUORADFC430, FC431 (Sumitomo 3M Limited), ASAHI GUARD AG710, SURFLON S-382,SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Co., Ltd.),organosiloxane polymer KP341 (Shinetsu Chemical Co., Ltd.), etc. Theblending amount of the surfactants is usually 0.2 mass % or less,preferably 0.1 mass % or less, based on 100 mass % of the totalcomposition of the anti-reflective coating for lithography according tothe present invention. The surfactants may be added singly or two ormore of them may be added in combination.

In the present invention, as the solvents for dissolving theabove-described solid content such as polymer compounds, use may be madeof ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, propylene glycol,propylene glycol monomethyl ether, propylene glycol monomethyl etheracetate, propylene glycol propyl ether acetate, toluene, xylene, methylethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate,ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethylhydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl3-methoxypropionate, ethyl 3-methoxypropionate, ethyl3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethylpyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate,etc. The organic solvents may be used singly or in combination of two ormore of them.

Further, high boiling solvents such as propylene glycol monobutyl etheror propylene glycol monobutyl ether acetate may be mixed. Among thesolvents, propylene glycol monomethyl ether, propylene glycol monomethylether acetate, ethyl lactate, butyl lactate, and cyclohexanone arepreferred for increasing the leveling property.

As photoresist to be coated as an upper layer of the anti-reflectivecoating in the present invention, any of negative type and positive typephotoresists may be used. The photoresist includes achemically-amplified type resist which consists of a photoacid generatorand a binder having a group which is decomposed with an acid andincreases alkali dissolution rate, a chemically-amplified type resistconsisting of an alkali-soluble binder, a photoacid generator, and a lowmolecular compound which is decomposed with an acid and increases thealkali dissolution rate of the resist, a chemically-amplified resistconsisting of a photoacid generator, a binder having a group which isdecomposed with an acid and increases the alkali dissolution rate, and alow molecular compound which is decomposed with an acid and increasesthe alkali dissolution rate of the resist. The photoresist includes alsofluorine atom-containing polymer type photoresist as described in Proc.SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000)or Proc. SPIE, Vol. 3999, 365-374 (2000).

As the developer for the above-mentioned positive type photoresisthaving the anti-reflective coating for lithography formed by using theanti-reflective coating forming composition of the present invention,use may be made of aqueous solutions of alkalis, e.g., inorganic alkalissuch as sodium hydroxide, potassium hydroxide, sodium carbonate, sodiumsilicate, sodium metasilicate or aqueous ammonia, primary amines such asethylamine or n-propylamine, secondary amines such as diethylamine ordi-n-butylamine, tertiary amines such as triethylamine ormethyidiethylamine, alcohol amines such as dimethylethanolamine ortriethanolamine, quaternary ammonium salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide or choline, cyclic amines suchas pyrrole or piperidine, etc. Furthermore, a suitable amount ofalcohols such as isopropyl alcohol or surfactants such as nonionicsurfactant can be added to the aqueous solution of above-describedalkalis. Among these, a preferred developer includes quaternary ammoniumsalts, more preferably tetramethylammonium hydroxide and choline.

Now, the method for forming photoresist patterns will be described. On asubstrate for use in the production of precision integrated circuitelement (silicon/silicon dioxide coat substrate, silicon nitridesubstrate, glass substrate, ITO substrate or the like), ananti-reflective coating forming composition is coated by a suitablecoating method, for example, with a spinner, a coater or the like, andthereafter the substrate is baked to cure the composition to fabricatean anti-reflective coating. The film thickness of the anti-reflectivecoating is preferably 0.01 to 3.0 μm. The conditions of baking after thecoating are 80 to 250° C. for 0.5 to 120 minutes. Then, a photoresist iscoated, it is exposed to light through a predetermined mask, developed,rinsed and dried to obtain a good photoresist pattern. If necessary,post exposure bake (PEB) may be performed. In addition, it is able toform a desired pattern on the substrate by removing by dry etching apart of the anti-reflective coating which a photoresist was removed bydevelopment in the previous step.

The anti-reflective coating produced from the composition for forminganti-reflective coating according to the present invention in which apolymer compound having repeating structural unit containing halogenatom is contained has a property of absorbing efficiently irradiationlight with a wavelength of 157 nm. Therefore, the coating exerts anexcellent effect of preventing reflection light from a substrate, andthus a photoresist pattern being an upper layer can be satisfactorilyformed. In addition, the anti-reflective coating produced from thecomposition for forming anti-reflective coating according to the presentinvention in which a polymer compound having repeating structural unitcontaining halogen atom has a relatively high dry etching rate owing toinclusion of halogen atom, and can control dry etching rate by changingthe content of halogen atom.

The anti-reflective coating formed from the composition for forminganti-reflective coating according to the present invention can be usedby selecting process condition as a coating having the followingfunctions: a function of preventing reflection light, a function ofpreventing a mutual interaction between a substrate and a photoresist, afunction of preventing an adverse effect to a substrate by a materialused in the photoresist or a substance generated on exposure to thephotoresist, or a function of preventing an adverse effect to aphotoresist by a substance generated from the substrate on exposure tolight or heating.

Hereinafter, the present invention will be described based on examplesand comparative examples but the present invention is not limitedthereto.

SYNTHESIS EXAMPLE 1 Synthesis of Concrete Example [4-1]

After 13.09 g of 2-bromoethyl methacrylate and 2.44 g of2-hydroxypropylmethacrylate were dissolved in 54 g of propylene glycolmonomethyl ether, the atmosphere was replaced with nitrogen. Theresulting solution was warmed to 70° C., and then a solution of 0.47 gof azobisisobutyronitrile dissolved in 10 g of propylene glycolmonomethyl ether was added dropwise. The resulting solution wassubjected to a reaction under nitrogen atmosphere for 24 hours to obtaina solution of polymer compound of concrete example [4-1]. The resultingpolymer compound was subjected to GPC analysis and had a weight averagemolecular weight (Mw) of 31,000 in terms of standard polystyrene.

SYNTHESIS EXAMPLE 2 Synthesis of Concrete Example [4-2]

After 11.23 g of 2,2,2-tribromoethyl methacrylate and 4.3 g of2-hydroxypropylmethacrylate were dissolved in 54 g of propylene glycolmonomethyl ether, the atmosphere was replaced with nitrogen. Theresulting solution was warmed to 70° C., and then a solution of 0.47 gof azobisisobutyronitrile dissolved in 10 g of propylene glycolmonomethyl ether was added dropwise. The resulting solution wassubjected to a reaction under nitrogen atmosphere for 24 hours to obtaina solution of polymer compound of concrete example [4-2]. The resultingpolymer compound was subjected to GPC analysis and had a weight averagemolecular weight of 22,000 in terms of standard polystyrene.

SYNTHESIS EXAMPLE 3 Synthesis of Concrete Example [4-2]

After 17.72 g of 2,2,2-tribromoethyl methacrylate and 1.7 g of2-hydroxypropylmethacrylate were dissolved in 70 g of propylene glycolmonomethyl ether, the atmosphere was replaced with nitrogen. Theresulting solution was warmed to 70° C., and then a solution of 0.58 gof azobisisobutyronitrile dissolved in 10 g of propylene glycolmonomethyl ether was added dropwise. The resulting solution wassubjected to a reaction under nitrogen atmosphere for 24 hours to obtaina solution of polymer compound of concrete example [4-2]. The resultingpolymer compound was subjected to GPC analysis and had a weight averagemolecular weight of 9,500 in terms of standard polystyrene.

SYNTHESIS EXAMPLE 4 Synthesis of Concrete Example [4-7]

After 10.00 g of brominated bisphenol A epoxy resin (manufactured byTohto Kasei Co., Ltd.; trade name: YDB-400; weight average molecularweight: 700) was dissolved in 21.33 g of propylene glycol monomethylether, 4.12 g of 2-naphthalene carboxylic acid and 0.10 g of benzyltriethylammonium chloride were mixed therewith. The resulting mixturewas subjected to a reaction under nitrogen atmosphere at 130+ C. for 24hours to obtain a solution of polymer compound of concrete example[4-7]. The resulting polymer compound was subjected to GPC analysis andhad a weight average molecular weight of 900 in terms of standardpolystyrene.

SYNTHESIS EXAMPLE 5 Synthesis of Concrete Example [4-8]

After 20.00 g of brominated bisphenol A epoxy resin (manufactured byTohto Kasei Co., Ltd.; trade name: YDB-400; weight average molecularweight: 700) was dissolved in 50.25 g of propylene glycol monomethylether, 13.50 g of 3,5-dibromobenzoic acid and 0.30 g of benzyltriethylammonium chloride were mixed therewith. The resulting mixturewas subjected to a reaction under nitrogen atmosphere at 130° C. for 24hours to obtain a solution of polymer compound of concrete example[4-8]. The resulting polymer compound was subjected to GPC analysis andhad a weight average molecular weight of 1,000 in terms of standardpolystyrene.

SYNTHESIS EXAMPLE 6 Synthesis of Concrete Example [4-6]

After 50.00 g of brominated epoxy phenol novolak resin (manufactured byNippon Kayaku Co., Ltd.; trade name: BREN-304; content of bromine atom:42 mass %; substituted with c.a. 1.5 bromine atom per benzene ring) wasdissolved in 146 g of propylene glycol monomethyl ether, 33.78 g of9-anthracene carboxylic acid and 1.05 g of benzyl triethylammoniumchloride were mixed therewith. The resulting mixture was subjected to areaction under nitrogen atmosphere at 130° C. for 24 hours to obtain asolution of polymer compound of concrete example [4-6] (wherein n=1.5).The resulting polymer compound was subjected to GPC analysis and had aweight average molecular weight of 1,600 in terms of standardpolystyrene.

SYNTHESIS EXAMPLE 7 Synthesis of Concrete Example [4-4]

After 6.74 g of 2,2,2-trichloroethyl methacrylate and 2.79 g of2-hydroxypropylmethacrylate were dissolved in 80 g of propylene glycolmonomethyl ether, the atmosphere was replaced with nitrogen. Theresulting solution was warmed to 70° C., and then a solution of 0.48 gof 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) dissolved in 10 g ofpropylene glycol monomethyl ether was added dropwise. The resultingsolution was subjected to a reaction under nitrogen atmosphere for 24hours to obtain a solution of polymer compound of concrete example [44].The resulting polymer compound was subjected to GPC analysis and had aweight average molecular weight of 12,000 in terms of standardpolystyrene.

SYNTHESIS EXAMPLE 8 Synthesis of Concrete Example [4-5]

After 30 g of 20 mass % solution of copolymer (molar ratio 50:50) ofglycidyl methacrylate and 2-hydroxypropyl methacrylate in propyleneglycol monomethyl ether was mixed with 4.79 g of 4-iodobenzoic acid,0.12 g of benzyl triethyl ammonium chloride and 19.64 g of propyleneglycol monomethyl ether, the resulting mixture was subjected to areaction by heating at reflux under nitrogen atmosphere for 24 hours toobtain a solution of polymer compound of concrete example [4-5].

SYNTHESIS EXAMPLE 9 Synthesisis of Concrete Example [4-19]

After 20 g of 20 mass % solution of polyglycidyl methacrylate inpropylene glycol monomethyl ether was mixed with 6.21 g of 4-iodobenzoicacid, 0.12 g of benzyl triethyl ammonium chloride and 25.44 g ofpropylene glycol monomethyl ether, the resulting mixture was subjectedto a reaction by heating at reflux under nitrogen atmosphere for 24hours to obtain a solution of polymer compound of concrete example[4-19].

SYNTHESIS EXAMPLE 10

After 60 g of 2-hydroxypropyl methacrylate was dissolved in 242 g ofpropylene glycol monomethyl ether, the resulting solution was warmed to70° C. Thereafter, while the reaction solution was kept at 70° C., 0.6of azobisisobutyronitrile was added thereto, and then the resultingsolution was subjected to a reaction at 70° C. for 24 hours to obtain asolution of poly 2-hydroxypropyl methacrylate. The resulting polymercompound was subjected to GPC analysis and had a weight averagemolecular weight of 50,000 in terms of standard polystyrene.

SYNTHESIS EXAMPLE 11 Synthesis of Concrete Example [4-39]

After 10.00 g of brominated epoxy phenol novolak resin (manufactured byNippon Kayaku Co., Ltd.; trade name: BREN-304; content of bromine atom:42 mass %; substituted with c.a. 1.5 bromine atom per benzene ring) wasdissolved in 32.88 g of propylene glycol monomethyl ether, 11.63 g of3,5-diiodo salicylic acid and 0.29 g of benzyl triethylammonium chloridewere mixed therewith. The resulting mixture was subjected to a reactionunder nitrogen atmosphere at 130° C. for 24 hours to obtain a solutionof polymer compound of concrete example [4-39] (wherein n=1.5). Theresulting polymer compound was subjected to GPC analysis and had aweight average molecular weight of 2,000 in terms of standardpolystyrene.

SYNTHESIS EXAMPLE 12 Synthesis of Concrete Example [4-40]

After 10.00 g of brominated epoxy phenol novolak resin (manufactured byNippon Kayaku Co., Ltd.; trade name: BREN-304; content of bromine atom:42 mass %; substituted with c.a. 1.5 bromine atom per benzene ring) wasdissolved in 32.20 g of propylene glycol monomethyl ether, 11.18 g of2,4,6-tribromo-3-hydroxy benzoic acid and 1.05 g of benzyltriethylammonium chloride were mixed therewith. The resulting mixturewas subjected to a reaction under nitrogen atmosphere at 130° C. for 24hours to obtain a solution of polymer compound of concrete example[4-40] (wherein n=1.5). The resulting polymer compound was subjected toGPC analysis and had a weight average molecular weight of 3,800 in termsof standard polystyrene.

SYNTHESIS EXAMPLE 13 Synthesis of Concrete Example [4-41]

After 3.04 g of 2-(2,4,6-tribromophenoxy)ethylacrylate and 0.92 g of2-hydroxypropylacrylate were dissolved in 10 g of propylene glycolmonomethyl ether, the atmosphere was replaced with nitrogen. Theresulting solution was warmed to 70° C., and then a solution of 0.040 gof azobisisobutyronitrile dissolved in 6 g of propylene glycolmonomethyl ether was added dropwise. The resulting solution wassubjected to a reaction under nitrogen atmosphere for 24 hours to obtaina solution of polymer compound of concrete example [4-41]. The resultingpolymer compound was subjected to GPC analysis and had a weight averagemolecular weight of 12,000 in terms of standard polystyrene.

SYNTHESIS EXAMPLE 14 Synthesis of Concrete Example [4-42]

After 1.20 g of 2-(2,3,4,5-tetrabromo-6-methoxyphenoxy)ethylacrylate and0.29 g of 2-hydroxypropylacrylate were dissolved in 5 g ofcyclohexanone, the atmosphere was replaced with nitrogen. The resultingsolution was warmed to 70° C., and then a solution of 0.015 g ofazobisisobutyronitrile dissolved in 3.5 g of cyclohexanone was addeddropwise. The resulting solution was subjected to a reaction undernitrogen atmosphere for 24 hours to obtain a solution of polymercompound of concrete example [4-42]. The resulting polymer compound wassubjected to GPC analysis and had a weight average molecular weight of7,400 in terms of standard polystyrene.

EXAMPLE 1

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 1 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 2

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 2 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 3

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 3 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 4

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 4 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 5

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 5 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 6

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 6 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 7

10 g of a solution of propylene glycol monomethyl ether containing 2 gof a commercially available bromide of polyparavinylphenol (MaruzenPetrochemical Co., Ltd.; trade name: Maruka Lyncur MB) was mixed with0.5 g of tetramethoxymethyl glycoluril as a crosslinking agent and 0.05g of p-toluenesulfonic acid as a catalyst, and dissolved in 56.7 g ofpropylene glycol monomethyl ether as a solvent to obtain a solution.Then, the solution was filtered through a micro filter made ofpolyethylene having a pore diameter of 0.10 μm, and then, the solutionwas filtered through a micro filter made of polyethylene having a porediameter of 0.05 μm, to prepare a composition solution for forminganti-reflective coating.

EXAMPLE 8

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 7 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 9

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 8 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 10

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 9 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 11

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 11 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 12

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 12 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 13

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 13 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 14

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 14 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

EXAMPLE 15

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 12 was mixed with 6.0 g of tetrabutoxymethylglycoluril (product name: Cymel 1170; manufactured by Mitsui Cytec Co.,Ltd.) as a crosslinking agent and 0.6 g of pyridinium p-toluenesulfonicacid as a catalyst, and dissolved in 103.7 g of propylene glycolmonomethyl ether and 47.0 g of propylene glycol monomethyl ether acetateas solvents to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

COMPARATIVE EXAMPLE 1

10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 10 was mixed with 0.5 g of tetramethoxymethylglycoluril as a crosslinking agent and 0.05 g of p-toluenesulfonic acidas a catalyst, and dissolved in 56.7 g of propylene glycol monomethylether as a solvent to obtain a solution. Then, the solution was filteredthrough a micro filter made of polyethylene having a pore diameter of0.10 μm, and then, the solution was filtered through a micro filter madeof polyethylene having a pore diameter of 0.05 μm, to prepare acomposition solution for forming anti-reflective coating.

Dissolution Test in Solvent for Photoresist

The composition solutions for forming anti-reflective coating obtainedin Examples 1 to 15 and Comparative Example 1 were coated on siliconwafers by means of a spinner. The coated silicon wafers were heated at205° C. for 1 minute on a hot plate to form anti-reflective coatings(film thickness 0.10 μm). The anti-reflective coatings were dipped in asolvent used for resists, that is ethyl lactate and propylene glycolmonomethyl ether and as a result it was confirmed that the resultingcoatings were insoluble in these solvents.

Test of Intermixing with Photoresist

The composition solutions for forming anti-reflective coating obtainedin Examples 1 to 15 and Comparative Example 1 were coated on siliconwafers by means of a spinner. The coated silicon wafers were heated at205° C. for 1 minute on a hot plate to form anti-reflective coatings(film thickness 0.10 μm). On each anti-reflective coating was coated acommercially available photoresist solution (manufactured by ShipleyCompany; trade name: APEX-E) by means of a spinner. The coated waferswere heated at 90° C. for 1 minute on a hot plate. After exposure of theresists to light, post exposure bake (PEB) was performed at 90° C. for1.5 minute. After developing the photoresists, the film thickness of theanti-reflective coatings was measured and no change was confirmed in thefilm thickness. Thus it was confirmed that no intermixing occurredbetween the anti-reflective coatings obtained from anti-reflectivecoating solutions prepared in Examples 1 to 15 and Comparative Example 1and the photoresist layers.

Test on Optical Parameter

The composition solutions for forming anti-reflective coating obtainedin Examples 1 to 15 and Comparative Example 1 were coated on siliconwafers by means of a spinner. The coated silicon wafers were heated at205° C. for 1 minute on a hot plate to form anti-reflective coatings(film thickness 0.06 μm). On each anti-reflective coating, refractiveindex (n) and attenuation coefficient (k) at a wavelength of 157 nm weremeasured with a spectroscopic ellipsometer (manufactured by J. A.Woollam Co., VUV-VASE VU-302). The results of the measurement are shownin Table 1. In addition, Table 2 shows the content (mass %) of halogenatom in the solid content in the composition of Examples together withattenuation coefficient (k).

TABLE 1 Refractive index Attenuation coefficient (n) (k) Example 1 1.790.31 Example 2 1.79 0.40 Example 3 1.78 0.48 Example 4 1.68 0.30 Example5 1.73 0.36 Example 6 1.64 0.29 Example 7 1.80 0.39 Example 8 1.82 0.25Example 9 1.72 0.25 Example 10 1.69 0.32 Example 11 1.70 0.46 Example 121.74 0.39 Example 13 1.81 0.30 Example 14 1.78 0.32 Example 15 1.65 0.36Comparative 1.75 0.19 Example 1

TABLE 2 Content of halogen atom Attenuation coefficient (mass %) (k)Example 1 27 0.31 Example 2 38 0.40 Example 3 49 0.48 Example 8 27 0.25Example 9 19 0.25 Example 10 25 0.32

From these results, it is understood that the anti-reflective coatingmaterial of the present invention has a satisfactorily high attenuationcoefficient k for a light of a wavelength of 157 nm, and can control thek value in a range of 0.2 to 0.48 by changing the kind or content ofhalogen atom, thereby providing excellent bottom type organicanti-reflective coatings. In addition, Examples 1 to 3, 9 and 10 inTable 2 shows that in case where the anti-reflective coatings containthe same kind of halogen atom, attenuation coefficient k increases withthe increase of its content. Further, from the comparison of the contentof halogen atom and the attenuation coefficient k in Examples 1, 2 and8, it is understood that bromine atom has a larger effect on the k valuethan chlorine atom, that is, bromine atom can afford a large attenuationcoefficient k in a lower content compared with chlorine atom. From thecomparison of Examples 1 and 10, it is understood that bromine atom hasan effect on the k value comparable with iodine atom.

INDUSTRIAL APPLICABILITY

The present invention provides a composition for forming anti-reflectivecoating having a strong absorption of light at a wavelength of 157 nm.The anti-reflective coating obtained from the composition efficientlyabsorbs reflection light from a substrate.

The present invention provides a composition for forming anti-reflectivecoating for lithography which effectively absorbs reflection light froma substrate when irradiation light from F2 excimer laser (wavelength 157nm) is used for micro-processing, and which causes no intermixing withphotoresist layer

Further, the present invention provides a method of controllingattenuation coefficient k of anti-reflective coating. The control ofattenuation coefficient k is carried out by changing the content ofhalogen atom in the solid content of the composition for forminganti-reflective coating. The control method enables modification incharacteristics of anti-reflective coatings so as to suit the kind orrequired characteristics of photoresists.

1. A composition for forming anti-reflective coating, comprising: asolid content and a solvent, and a proportion of at least one halogenatom selected from the group consisting of bromine atom and iodine atomin the solid content is 10 mass % to 60 mass %, and the solid contentcontains a polymer compound selected from the group consisting of abisphenol A derivative resin, a phenol novolak derivative resin, and apolyparavinylphenol derivative resin, the polymer compound having arepeating structural unit containing the at least one halogen atom. 2.The composition for forming anti-reflective coating according to claim1, wherein the repeating structural unit further contains acrosslink-forming substituent.
 3. The composition for forminganti-reflective coating according to claim 1, wherein the polymercompound further has a repeating structural unit containing acrosslink-forming substituent.
 4. The composition for forminganti-reflective coating according to claim 1, wherein the polymercompound contains at least 20 mass % of the at least one halogen atomselected from the group consisting of bromine atom and iodine atom. 5.The composition for forming anti-reflective coating according to claim1, wherein the polymer compound has a weight average molecular weight of700 to 1,000,000.
 6. A composition for forming anti-reflective coatingcharacterized in that the composition comprises a solid content and asolvent, and a proportion of at least one halogen atom selected from thegroup consisting of bromine atom and iodine atom in the solid content is10 mass % to 60 mass %, wherein the solid content contains a polymercompound having a repeating structural unit comprising the at least onehalogen atom and a crosslink-forming substituent, wherein the repeatingstructural unit is represented by formula (1)

wherein L is a bonding group constituting a main chain of the polymercompound, M is a linking group containing at least one linking groupselected from —C(═O)—, —CH₂— or —O—, or a direct bond, X is bromine atomor iodine atom, t is a number of 1 or 2, u is a number of 2, 3 or 4, vis a number of the repeating structural units contained in the polymercompound and is a number of 1 to 3,000.
 7. The composition for forminganti-reflective coating according to claim 1, wherein the solid contentfurther contains a crosslinking agent having at least twocrosslink-forming substituents.
 8. An anti-reflective coating producedby coating the composition for forming anti-reflective coating accordingto claim 1, on a semiconductor substrate, and baking it, wherein theanti-reflective coating has an attenuation coefficient k to a light at awavelength of 157 nm ranging from 0.20 to 0.50.
 9. A method of formingan anti-reflective coating for use in a manufacture of a semiconductordevice, comprising the steps of: coating the composition for forminganti-reflective coating according to claim 1, on a substrate, and bakingit.
 10. A method of forming an anti-reflective coating for use in amanufacture of a semiconductor device by use of a light of wavelength157 nm, comprising the steps of: coating the composition for forminganti-reflective coating according to claim 1, on a substrate, and bakingit.
 11. A method of forming a photoresist pattern for use in amanufacture of a semiconductor device comprising the steps of: coatingthe composition for forming anti-reflective coating according to claim1, on a semiconductor substrate and baking it to form an anti-reflectivecoating; forming a photoresist layer on the anti-reflective coating;exposing the semiconductor substrate covered with the anti-reflectivecoating and the photoresist layer with F2 excimer laser (wavelength 157nm); and developing the exposed photoresist layer.